<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>talk</title>
    <style type="text/css">
        div {
            position: relative;
            width: 500px;
            height: 300px;
            border: 1px solid black;
            -webkit-border-radius: 50%;
            -moz-border-radius: 50%;
            -ms-border-radius: 50%;
            -o-border-radius: 50%;
            border-radius: 50%;
            font-size: 24px;
            font-weight: bold;
            text-align: center;
            line-height: 300px;
        }

        div:before,
        div:after {
            position: absolute;
            content: "";
            display: block;
            border: 1px solid black;
            -webkit-border-radius: 50%;
            -moz-border-radius: 50%;
            -ms-border-radius: 50%;
            -o-border-radius: 50%;
            border-radius: 50%;
        }

        div:before {
            width: 50px;
            height: 50px;
            bottom: -25px;
            right: 25px;
        }

        div:after {
            width: 20px;
            height: 20px;
            bottom: -50px;
            right: 0;
        }
    </style>
</head>
<body>
<div>大家好，欢迎来到慕课网！</div>
</body>
</html>